Laws of thermodynamics : Changes in internal energy.

The specific heat of air at constant volume is 0.175 cal/gm deg Celsius

a) By how much does the internal energy of 5 gm of air change as it is heated from 20 deg to 400 deg?

(b) Suppose that 5gm of air is adiabatically compressed so as to raise its temperature from 20deg to 400 deg. How much work must be done on the air to compress it?